A general example of the syringes comprises a front-assembly, which is provided with an injection needle, a needle-base member, a protector cap and a connection hub, secured to a leading end of an injection cylinder (for example, see Patent Literature 1).
The connection hub has a connection portion hermetically and securely fixed to the leading end of the injection cylinder and has the needle-base member detachably attached thereto. The injection needle has a base end portion secured to the needle-base member and a protector cap is removably fitted onto the injection needle so as to cover a periphery thereof.
The base end portion of the injection needle is assuredly secured to the needle-base member and is bonded thereto with an epoxy adhesive consisting mainly of bisphenol A-type epoxy resin. More specifically, the needle-base member has the leading end portion provided with a hole for inserting the base end portion of the injection needle. The adhesive is hermetically filled into a space between the base end portion of the injection needle and the needle-base base member so as not to cause a bad appearance such as roping. Conventionally, such an adhesive has a viscosity set to about 10000 mPa·s by adjusting the content of denatured aliphatic epoxy resin.
Although the epoxy resin adhesive agent is cured by heating, there are many cases where the needle-base member is formed from polypropylene resin and the like synthetic resin material. Adopted for the adhesive are those of the type that cures quickly at a relatively low temperature of about 100 degrees C., for example, below 120 degrees C., so that the needle-base member does not suffer from thermal deformation upon curing.
And the injection needle and the front-assembly with this injection needle are assembled to an injection cylinder during the production process of the syringe and thereafter are subjected to a sterilization treatment with dump and heat by vapor at a temperature of, for example, 121 degrees C. in an aseptic room before they are filled with injection medicine or are assembled to an injection cylinder prefilled with the injection medicine.    Patent Literature 1: Utility Model Application Laid-Open No. 10-211280